leetcode summary-section II-优快云博客

151 Reverse Words in a String

 1 class Solution {
 2 public:
 3     void reverseWords(string &s) {
 4         string result;
 5         for (int i = s.size() - 1; i >= 0;)    {
 6             while (i >= 0 && s[i] == ' ') {
 7                 i--;
 8             }
 9             if (i < 0) {
10                 break;
11             }
12             
13             string word;
14             while (i >= 0 && s[i] != ' ') {    
15                 word += s[i];
16                 i--;
17             }
18             reverse(word.begin(), word.end());
19             if (!result.empty()) {
20                 result += ' ';
21             }
22             result += word;
23         }
24         s = result;
25     }
26 };

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细节处理。

186 Reverse Words in a String II

 1 class Solution {
 2 public:
 3     void reverseWords(string& s) {
 4         reverse(s, 0, s.length);
 5         for (int i=0, j=0; j<=s.length; j++) {
 6             if (j==s.length || s[j]==' ') {
 7                 reverse(s, i, j);
 8                 i =  j + 1;
 9             }
10         }
11     }
12  
13     void reverse(string& s, int begin, int end) {
14         while (begin < end - 1) {
15             swap(s[begin], s[end - 1]);
16             begin++; end--;
17         }
18     }
19 };